The aim of this program is to gain further insight into the underlying mechanisms of biological aging by investigating biochemical alterations associated with specific age-dependent processes throughout the lifespan of the rat. A variety of research interests and experimental approaches will be focussed upon the biochemical nature of those factors which regulate the chronological development, the adaptive capacity, and the changes which accompany advancing age of a few, select systems. The age-dependent processes included in this program are enzyme inducibility, behavior of hormone receptor systems, and fidelity of transcription and translation. BIBLIOGRAPHIC REFERENCES: Roth, G.S., and Adelman, R.C., Age Related Changes in Hormone Binding by Target Cells and Tissues: Possible Role in Altered Adaptive Responsiveness, Exper. Gerontol. 10, 1 (1975). Britton, G.W., Rotenberg, S., and Adelman, R.C., Impaired Regulation of Corticosterone Levels during Fasting in Aging Rats, Biochem. Biophys. Res. Commun. 64, 184 (1975).